web: cleanup messages implementation (#386)

* web: rebuild messages without template objects

* web: show error message when ws connection fails

* web: show error message when siteshell page not found

* web: fix spinner size for loading

* web: fix linting error

web/src/elements/messages/Message.ts

@@ -0,0 +1,53 @@
+import { customElement, html, LitElement, property, TemplateResult } from "lit-element";
+
+export interface APIMessage {
+    level_tag: string;
+    tags?: string;
+    message: string;
+}
+
+const LEVEL_ICON_MAP: { [key: string]: string } = {
+    error: "fas fa-exclamation-circle",
+    warning: "fas fa-exclamation-triangle",
+    success: "fas fa-check-circle",
+    info: "fas fa-info",
+};
+
+@customElement("ak-message")
+export class Message extends LitElement {
+
+    @property({attribute: false})
+    message?: APIMessage;
+
+    @property({type: Number})
+    removeAfter = 3000;
+
+    @property({attribute: false})
+    onRemove?: (m: APIMessage) => void;
+
+    createRenderRoot(): ShadowRoot | Element {
+        return this;
+    }
+
+    firstUpdated(): void {
+        setTimeout(() => {
+            if (!this.message) return;
+            if (!this.onRemove) return;
+            this.onRemove(this.message);
+        }, this.removeAfter);
+    }
+
+    render(): TemplateResult {
+        return html`<li class="pf-c-alert-group__item">
+            <div class="pf-c-alert pf-m-${this.message?.level_tag} ${this.message?.level_tag === "error" ? "pf-m-danger" : ""}">
+                <div class="pf-c-alert__icon">
+                    <i class="${this.message ? LEVEL_ICON_MAP[this.message.level_tag] : ""}"></i>
+                </div>
+                <p class="pf-c-alert__title">
+                    ${this.message?.message}
+                </p>
+            </div>
+        </li>`;
+    }
+
+}